chore: add local firebase emulator config

Author: stfsy

firebase.json

@@ -0,0 +1,11 @@
+{
+    "emulators": {
+        "firestore": {
+            "port": 9999
+        },
+        "ui": {
+            "enabled": true,
+            "port": 4000
+        }
+    }
+}